None of the companies on STJ permit their cars to be taken to STT, but you could rent a car on STT and take it to STJ.

Thank you for the info! I phoned budget and they only have STT - to STJ...

I guess there's no option at all then to rent a car in St.John and take it to STT?

No, there are no chain car rental places on STJ, just local folks and they all have very high fines if you take the car off the island.

If you want to take your car between STT and STJ, you should just rent on STT. Hertz will not let you do this, but the others will. If you want local folks, people speak fondly of Dependable.

We have only used St John Car Rental, and I really like them except you have to be there before they close at 5 or you're not getting a car that day.

Been down 5 years in a row now and have always reserved and picked up a jeep at Budget at the airport.
We've never had to wait in a line or wonder where our vehicle was - alway right up in the lot ready to go.
I've been reading about the headaches on other threads. Maybe we've just been lucky....
We drive to Red Hook and take the car ferry to STJ for a week. Have always had a clean, reliable vehicle and
that way you have the freedom of you own transportation your entire stay. Never have been on a taxi.
For us, that is definitely the way to go. But everybody thinks differently.